Edith Bruckner-Kardoss

EFFECTS OF MICROBIAL FLORA ON CARDIAC OUTPUT AND OTHER ELEMENTS OF BLOOD CIRCULATION.

Summary Cardiac output in young adult germfree rats was found to be approximately 30% lower than in conventional controls. Concomitantly, signs of mild hemoconcentration were observed in the germfree group, which may be linked to changed water balance in these animals. The reduced work performance of the heart indicated in the germfree group is associated with the absence of a microbial flora.

Cecal Enlargement, Cardiac Output, and O2 Consumption in Germfree Rats

Summary Germ free rats have cardiac output and O2 consumption values respectively 30% and 24% lower than found in comparable conventional rats. Surgical removal of the enlarged cecum typical for these animals resulted in cardiac output values similar to those obtained with conventional rats, while O2 consumption increased significantly to levels only slightly lower than seen in the conventional control group. No significant difference in body temperature was found between comparable groups of germfree and conventional rats.

Oxidation-Reduction Potentials in Gecal Contents of Germfree and Conventional Rats.∗

Summary Oxidation-reduction potentials in cecal contents of germfree rats were 250 to 300 mV more positive than in the contents of conventional animals. Treatment of germ-free rats with cecal contents from conventional rats showed that 4 hours later these animals demonstrated oxidation-reduction values comparable to those found in conventional rats. The more positive oxidation-reduction potential thus appears directly related to the absence of an intestinal micro-flora.

Glucose Tolerance, Insulin and Catecholamine Levels in Germfree Rats

Summary Glucose was administered intravenously to 50- and 100-day-old GF and CV rats. Fasting blood glucose levels in GF and CV rats were found to be comparable. Glucose tolerance tests showed that GF and CV rats clear glucose from the blood at a similar rate. Although insulin concentrations in 100-day-old GF rats tended to be somewhat lower than in CV rats, the percentage increase during the 30-min period after glucose administration was similar, and matched the increase in blood glucose. Levels of plasma catecholamines were analyzed fluorometrically and were found to be comparable in 100-day-old GF and CV rats. It was concluded that insulin insufficiency plays no role in the syndrome of metabolic anomalies demonstrated by the germfree rat.

A model system for the in vivo determination of the thrombolytic effect of plasminogen activators

An in vivo model system for measuring the thrombolytic efficiency of plasminogen activators was used. The formation of radiolabelled microthrombi was induced by infusion with I-125 labelled fibrinogen and thrombin. Reactive fibrinolysis was inhibited by administration of suboptimal levels of e-aminocaproic acid. The thrombolytic and subsequent fibrinolytic events were followed in the capillary bed of the lungs of anesthetized rats by external monitoring of the I-125 activity over the lung field. The model was successfully employed to demonstrate the thrombolytic effect of plasminogen activator produced by a transplanted spontaneous rat prostate adenocarcinoma cell line (PA III). The system proved to be reproducible with detection limits of 6000 I.U. using the PA-III cell line derived activator.